The troupe pooled their efforts for the unnecessary new adaptation of “Murder on the Orient Express,” the Agatha Christie classic that first became a movie in 1974. That version also featured an all-star ensemble (Albert Finney, Lauren Bacall, Ingrid Bergman, Sean Connery, the list goes on). Their whodunit parlor game seduced the camera, each performer playing a pivotal role in mounting the central mystery: Who killed the enigmatic American businessman aboard the titular train?

This time around, it’s hard to care. It’s hard to grasp what’s unfolding before our eyes. It’s hard to understand why so many of the scenes outside the locomotive appear to contain gaudy CGI while certain others look like painterly bombast. (Strange, considering Branagh shot the movie on high-quality 65mm film.) It’s hard to recall the many characters’ complex names: Princess Dragomiroff, Gerhard Hardman, Dr. Arbuthnot, Pilar Estravados. Fail, and you risk being left behind while Christie’s flowery Belgian gumshoe, Hercule Poirot, played by a scenery-chewing and well-mustachioed Branagh, investigates the execution. Poirot is the type of fella who obsesses over symmetry and says “oeufs” ― the French word for “eggs” ― in whimsical conversation.

(20th Century Fox)

Excuse the blasphemy, Agatha Christie acolytes, but “Murder on the Orient Express,” published in 1934, is a dull addition to the mystery genre. Told entirely from Poirot’s perspective, it’s nearly impossible to piece together enough clues to outwit the detective. Christie’s smooth prose keeps the novel flowing, but it’s not enough to save this big-screen iteration. Prepare for a meaningless thrill ride that couldn’t be less thrilling if it tried.

It’s a curious thing, this particular “Orient Express.” Written by Michael Green (“Logan,” “Blade Runner 2049”), the movie begins with a sweeping adventure scene that introduces Poirot as an exacting dandy ready to retire his world-renowned sleuthing skills. He boards a first-class train in Istanbul, heading to Calais and expecting much-needed R&R. But Edward Ratchett (Depp), who claims to be an art dealer, fears he is a marked man. He pleads for Poirot’s protection, which leads to the movie’s single most comprehensible moment: Branagh telling Depp, “I do not like your face.”

Finally, something the audience can appreciate.

(20th Century Fox)

Ratchett is murdered in the night, launching an impenetrable round of Clue, cut together with jarring shot compositions that seem to think we know more about these underwritten characters than we actually do. Evidence is entered, timelines are recounted, motivations are weighed, backstories are introduced ― all to very little end. The outcome, revealed in a sermon from Poirot that remains faithful to Christie’s text, recaps events we never saw firsthand and inter-character connections we were never curious to glean. Most attempts at banter ― between Rachett and Pfeiffer’s saucy “husband-hunting” actress character, for example ― feel culled from longer scenes that were butchered and rendered lifeless.

There is at least one moment that demonstrates what this movie could have been. Maybe half an hour into it, the camera pans through the train’s dining cabin, canvassing the suspects, who sit around looking wealthy and culpable. This slick tracking shot is a bewitching beckon, so self-aware about its own delicious coyness that it almost works as high camp. Before us, a lineup of potential assassins, plucked from across the globe, partake in a devilish blame game. We feast on the cornucopia of first-rate performers who’ve been handed an excuse to deliver hammy material about a crime carried out in the dark of the night.